Nano-gold based ELISA versus traditional ELISA for early detection of Trichinella spiralis crude excretory antigen in experimentally infected mice

Background: The main disadvantage of ELISA in diagnosis of trichinosis is the false-negative result especially during early infections. Nanoparticle-based immunoassays were developed for serodiagnosis of several parasitic diseases. Objective: Comparison of nano-gold based ELISA (NGB-ELISA) to the traditional sandwich ELISA for the early detection of T. spiralis crude excretory antigen (CEA) in serum and fecal samples of T. spiralisexperimentally infected mice. Material and Methods: In the present study, 180 mice were distributed in three groups. In GI (T. spiralisinfected group) 108 mice were infected. Infection was confirmed by the presence of encysted T. spiralis larvae in excised muscle specimens on the 28th day post-infection (dpi). For microscopic examination by direct smear and MIFC methods and detection of T. spiralis CEA, stool samples were collected on the 2nd, 4th, 6th, 8th, and 10th dpi; then mice were sacrificed, and blood samples were collected on the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, 21st, and 28th dpi. The study included two control groups; GII (specificity group) included 18 mice infected with Cryptosporidium spp., T. gondii, and S. mansoni (6 mice each) for testing cross-reactivity. Stool and serum samples were collected on the day of sacrifice (30th dpi for Cryptosporidium, 60th dpi for T. gondii and S. mansoni). The GIII (sensitivity control group) included 54 non-infected mice. Mice were subjected to stool and blood samples collection, and sacrification as described in T. spiralis-infected group. Results: While microscopic examination of direct smear proved negative for detection of T. spiralis diagnostic stages, MIFC technique showed diagnostic larvae and adult worms in only 5% of mice sacrificed on the 6th dpi. For T. spiralis CEA detection, the difference between NGB-ELISA and traditional ELISA was not significant in fecal samples. In contrast, NGB-ELISA showed significantly higher number of positive serum samples than traditional ELISA, detecting the infection earlier (2nd versus 10th dpi) with a diagnostic Conclusion: The NGB-ELISA for detection of T. spiralis CEA in serum samples was superior to the traditional ELISA as it revealed a significantly higher number of positive cases. It verified the infection earlier and was more sensitive until the 14th dpi with a specificity of 100%. Regarding coproantigens, no significant differences were noticed between either ELISAs.